1. Field of the Invention:
The present invention relates generally to safety systems for chemical and nuclear reactors and more particularly to a passive filtered venting system.
2. Description of the Prior Art:
The nuclear industry has given considerable attention to the problem of degraded core and core melt accidents in nuclear reactors. One aspect of that problem is that of containment failure due to long term overpressure when fission products are released from the core to the containment atmosphere. The Industry Degraded Core Rulemaking (IDCOR) Program, Sponsored by the Nuclear Industry in July 1983 published its Technical Report 19.1 entitled Alternate Containment Concepts which contains an evaluation of various containment concepts for potential mitigation or delay of containment failure during accidents beyond the design basis. Generally, that study concluded that the reduction of the risk of inadvertantly releasing material to the atmosphere is higher with the vent-filter systems that have more components. Conversely, however, such systems are more prone to component failure and operator error.
While the removal of heat from the containment is essentially an active process, the venting of the containment is preferred to be passive in that there is no power requirement, minimal test and maintenance requirements, high reliability and simple operation. The most common form of passive vent is the well known rupture disc which simply gives way at a preselected design pressure. A rupture disc will reliably open at the design pressure, it will not close when the containment pressure drops below that which requires venting.